Monolithically Integrated Lithium Niobate On Silicon

Abstract

A material according to the present technology may include a silicon substrate, a single crystal oxide buffer layer formed on the silicon substrate, and a layer of lithium niobate formed on the single crystal oxide buffer layer. A method of producing a material according to the present technology may include the steps of forming a single crystal oxide buffer layer on a silicon substrate and forming a layer of lithium niobate on the single crystal oxide buffer layer.

What is claimed is: 
     
         1 . A material comprising:
 a silicon substrate;   a single crystal oxide buffer layer formed on the silicon substrate; and   a layer of lithium niobate formed on the single crystal oxide buffer layer.   
     
     
         2 . The material of  claim 1 , wherein the silicon substrate comprises one of:
 a silicon wafer; or   a device silicon layer of a silicon on insulator (SOI) wafer.   
     
     
         3 . The material of  claim 1 , wherein the single crystal oxide buffer layer comprises one of:
 a spinel buffer;   bixbyite buffer;   wurtzite buffer;   zinc oxide; or epitaxial oxide.   
     
     
         4 . The material of  claim 3 , wherein the single crystal oxide buffer layer comprises the bixbyite buffer and the bixbyite buffer comprises a composition defined as R1 x R2 1−x O 3 , wherein R1 or R2 can be any Group 3 element that normally forms in a bixbyite crystal structure. 
     
     
         5 . The material of  claim 1 , wherein the single crystal oxide buffer layer comprises at least one of: aluminum oxide (Al 2 O 3 ); gadolinium oxide (Gd 2 O 3 ), neodymium oxide (Nd 2 O 3 ), yttrium oxide (Y 2 O 3 ), praseodymium oxide (Pr 2 O 3 ), erbium oxide (Er 2 O 3 ), and indium oxide (In 2 O 3 ). 
     
     
         6 . The material of  claim 1 , wherein the layer of lithium niobate is:
 epitaxially grown on the silicon substrate via the single crystal oxide buffer layer; and   comprises a thickness of in a range of 1 nanometer (nm) to about 1 micron (μm).   
     
     
         7 . The material of  claim 1 , wherein the layer of lithium niobate has a thickness of greater than or equal to 8 unit cells. 
     
     
         8 . The material of  claim 1 , wherein the layer of lithium niobate is at least one of ferroelectric and piezoelectric. 
     
     
         9 . A waveguide device comprising:
 a silica layer;   a single crystal oxide buffer layer formed on the silica layer, wherein:
 the single crystal oxide buffer layer comprises a top surface and a bottom surface; and 
 the bottom surface of the single crystal oxide buffer layer contacts the silica layer; and 
   a layer of lithium niobate is formed on a portion of the top surface of the single crystal oxide buffer layer.   
     
     
         10 . The waveguide device of  claim 9 , wherein the single crystal oxide buffer layer comprises:
 a bixbyite buffer; and   a thickness of from about 1 nanometer (nm) to about 1 micron (μm).   
     
     
         11 . The waveguide device of  claim 10 , wherein the bixbyite buffer comprises a composition defined as R1×R21−xO3, wherein R1 or R2 can be any Group 3 element that normally forms in a bixbyite crystal structure. 
     
     
         12 . The waveguide device of  claim 9 , wherein the single crystal oxide buffer layer comprises:
 an epitaxial oxide; and   a thickness of from about 1 nanometer (nm) to about 1 micron (μm).   
     
     
         13 . The waveguide device of  claim 9 , wherein the lithium niobate layer:
 is epitaxially grown on the silica layer via the single crystal oxide buffer layer; and   comprises a thickness of greater than or equal to 8 unit cells.   
     
     
         14 . The waveguide device of  claim 9 , wherein the silica layer comprises one of:
 a silicon wafer; or   a device silicon layer of a silicon on insulator (SOI) wafer.   
     
     
         15 . A method of producing a material, the method comprising:
 forming a single crystal oxide buffer layer on a silicon substrate; and   forming a layer of lithium niobate on the single crystal oxide buffer layer.   
     
     
         16 . The method of  claim 15 , wherein forming the layer of lithium niobate comprises epitaxially growing the layer of lithium niobate on the silicon substrate via the single crystal oxide buffer layer, wherein the layer of lithium niobate comprises a thickness in a range of 10 to 120 nanometers. 
     
     
         17 . The method of  claim 15 , wherein forming the single crystal oxide buffer layer on the silicon substrate comprises forming the single crystal oxide buffer layer having a thickness in a range from about 1 nm to about 10 μm on the silicon substrate. 
     
     
         18 . The method of  claim 15 , wherein forming the layer of lithium niobate on the single crystal oxide buffer layer comprises:
 using radio frequency (RF) sputtering to form the layer of lithium niobate on the single crystal oxide buffer layer at a predetermined thickness from a lithium-rich sputtering target.   
     
     
         19 . The method of  claim 15 , wherein forming the layer of lithium niobate comprises:
 initially depositing a seed layer of lithium niobate on the single crystal oxide buffer layer; and   depositing a remainder of the layer of lithium niobate to a predetermined thickness using metal-organic chemical vapor deposition (MOCVD).   
     
     
         20 . The method of  claim 15 , wherein:
 the silicon substrate comprises Si;   forming the single crystal oxide buffer layer comprises forming the single crystal oxide buffer layer on the Si; and   the method further comprises:
 annealing, at an elevated temperature and in the presence of oxygen, a product of forming the single crystal oxide buffer layer on the Si.